Once you have created your tax rates, you will need to then link them to your products.
To do this, you will first want to navigate to Maintenance -> Products -> Product Maintenance. In here, search for the product you wish to link the tax rate to and then click the Edit icon on the left-hand side. This will take you to the product editor.
In the product edit screen, click the tab which says Tax Rates.
To link the tax rate, simply check the tax rate you wish to link the product to. Once you have done this, click Save and the product should now be tax linked.